Vehicle mounted electrical generator system

ABSTRACT

A vehicle mounted AC generator system having an AC generator mounted outside the engine/transmission compartment and connected by drive shaft with universal joints and a belt driven RPM ratio device. The ratio is set to provide accurate AC generator RPM at a preselected engine RPM. The AC generator is mechanically engageable when certain conditions are met and is disconnected when other conditions are present, including an operator emergency stop switch.

The present invention relates to electrical generators and morespecifically to electrical generators for use in vehicles.

BACKGROUND OF THE INVENTION

There has been a long-felt need for an AC electrical power source inlocations not served by electrical utilities. Usually these involveconstruction sites where the electrical power grid is not yet extendedto an individual site. In addition, there are sites that are so remotethat electricity is not available.

Typically, AC power generated by a vehicle has been accomplished y theuse of inverters which take DC voltage, step it up to well above 240volts and then electronically manipulate the DC signal so that some formof AC signal at either 120 volts or 240 volts is provided at an outletbox. The system shown in U.S. Pat. No. 6,157,175 is typical of suchsystems. These involve an alternator positioned in or near the enginecompartment and driven off of an accessory belt drive. The alternatorgenerates DC voltage which is then electronically boosted and thenchopped to produce a pseudo-AC wave. The problem with devices of thistype is significant expense associated with the alternator itself andthe complex electrical control system used to produce the pseudo-AC waveoutput. Furthermore, such systems are relatively incapable of sustainingmaximum or above maximum output for any length of time and lack reservecapacity to achieve really heavy-duty current output as when an arcwelder or other electrical power-consuming device is utilized with thesystem.

SUMMARY

The above invention relates to a vehicle-mounted AC electrical generatorsystem where the vehicle includes a prime mover and a compartment forthe prime mover. An AC electrical generator is positioned outside saidprime mover compartment and has a mechanical power input connection fordriving the AC electrical generator to produce electricity. The devicereceives mechanical power from the prime mover and transfers themechanical power to the AC electrical generator mechanical power inputconnection.

In another form, the invention relates to a method of adding an ACelectrical generator to a vehicle having a support frame and powered bya prime mover located in a prime mover compartment. The method comprisesthe steps of mounting the AC electrical generator outside the primemover compartment and in an available location in the support frame. Amechanical connection is provided between the prime mover and the ACelectrical generator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing of a vehicle and an AC electricalgenerator system embodying the present invention.

FIG. 2 is a schematic diagram of another electrical generator system forproviding AC electrical generation capacity when a vehicle isstationary.

FIG. 3 is a schematic diagram showing an alternate embodiment of thepresent invention adaptable for provision of electrical power while avehicle is moving.

FIG. 4 is a partial view of a vehicle in which the AC electricalgenerating system is installed looking from the front toward the aftsection of the vehicle.

FIG. 5 is a side fragmentary view of the vehicle of FIG. 4 taken onlines 5—5 of FIG. 4.

FIG. 6 is a plan view of the system of FIG. 4 taken on lines 6—6 of FIG.4.

FIG. 7 is a greatly enlarged longitudinal fragmentary section view of apower takeoff (PTO) shown in FIG. 4 and taken on lines 7—7 of FIG. 4.

FIG. 8 is an enlarged side view of an AC electrical generator mountingassembly used to support the AC generator shown in FIGS. 4 through 6.

DESCRIPTION OF THE SELECTED EMBODIMENT

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustratedherein and specific language will be used to describe the same. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended. Any alterations and further modificationsin the described processes, systems or devices, and any furtherapplications of the principles of the invention as described herein, arecontemplated as would normally occur to one skilled in the art to whichthe invention relates.

FIG. 1 shows a vehicle system 10 with which an AC electrical generatingsystem is incorporated. The existing vehicle components and AC generatoraccessories are demarked by a reference line A. The vehicle 10 has aframe, not illustrated in FIG. 1, but illustrated in FIG. 4 through FIG.8, which provides a support for a vehicle body, also not shown, and anengine 14 driving a transmission 16 through a primary mechanical output18 to function as a prime mover for vehicle 10.

Engine 14 may be any one of a variety of prime movers includingspark-ignited gasoline or natural gas fueled engine or a compressionignition diesel engine. It should be apparent to those skilled in theart that other forms of prime movers providing mechanical outputs may beincorporated. The transmission 16 may be one of a variety oftransmissions herein shown as an automatic transmission providing arotatable output shaft 20 for the vehicle 10.

The engine 14 is controlled by an engine control module (ECM) 22interconnected to engine 14 at 24. The interconnection between enginecontrol module 22 and engine 14 may vary widely according to the type ofengine and the desired control parameters. In most cases, the enginefuel supply system (not shown) is controlled by a computer in the (ECM)22 in accordance with an algorithm based on various engine operatingparameters such as engine RPM, required torque, ambient temperatures,absolute pressure and a host of other variables. The result is that theinterconnection between the engine control module 22 and engine 14through 24 is a two-way connection wherein parameter signals aretransmitted to the ECM and control signals are transmitted to the engine14.

In a number of vehicles, the transmission 16 has a more sophisticatedcontrol through a transmission control module 26 interconnected totransmission 16 through 28 and connected to engine control module 22through 30. The transmission control module 26, ECM 22, engine 14 andtransmission 16 are all coordinated so that the appropriate balance ofrequired power, fuel economy and emissions level is maintained.

In addition to the transmission control module 26, the vehicle 10 has anignition switch 32 connected to ECM 22 by line 34. The vehicle 10 alsohas an operator's switch 36 connected to ECM 22 by line 38 forcontrolling the power takeoff (PTO) described later. In addition, thevehicle 10 has a cruise control resume switch 40 connected to the ECM 22by line 42. In order to simplify the description of the presentinvention, the vehicle elements generally described by referencecharacter 10 will be given the same reference characters in FIG. 2 andFIG. 3 even though the AC power generation system will have differentelements cooperating with the vehicle components.

The present invention consists of applying a readily available, highlycommercially developed and relatively inexpensive AC generator to avehicle instead of the overly complicated DC generators and inverterspreviously applied to such vehicles. The elements set forth below allowthis to be achieved in a way that is consistent with heavy-dutyelectrical generation and convenience and safety of use. The ACgenerator system generally indicated by 12 comprises an AC generator 44that can be selected from various sizes and manufacturers. Measured inkilowatt output, it has been found that 5–15 kilowatts are readilyaccommodated within vehicles as set out below. It should be apparent tothose skilled in the art, however, that many other AC generators couldbe employed for this purpose. One of the advantages of an AC generatoris that it produces a perfect sine wave which replicates the sine waveproduced by utility companies as opposed to the modified or mock sinewave produced by standard inverters on the market. It is also a featureof AC generators that they are very robust and can easily handle highcontinuous current loadings as would be experienced in typicalconstruction site activities like welding and heavy-duty cutting ofmaterials.

The AC generator 44 is positioned in the vehicle outside of thecompartment for the prime mover consisting of the engine andtransmission as will be described in detail later. The AC generator hasa mechanical power input 46 which is adapted to receive a rotatableinput from an RPM ratio assembly. Assembly 48 is connected to a PTO unit50 via an appropriate mechanical link such as a shaft 52. PTO unit 50 isdriven from transmission 16 through an engageable and disengageablemechanical connection 54. A solenoid 56 mechanically connects with PTOunit 50 through a connection 58 to engage or disengage PTO unit 50 andthus drive the AC generator 44 as will be described later.

Solenoid 56 is of a type that is biased to a disengaged position in theabsence of an electrical signal and then urged to an engaged positionwhen an electrical signal is sent to solenoid 56 via line 60. Line 60 isconnected to a relay box 62 which enables engagement of solenoid 56 andtherefore mechanical operation of AC generator 44 only when certainconditions exist. The relay box receives input from the cruise controlresume button 40 via line 64 and from ignition switch 32 via line 66.Finally, the relay box receives an input from operator switch 36 vialine 68, and from ECM 22 via line 70, and from the transmission controlmodule via line 71.

The electrical output of AC generator 44 extends to output box 72 viapower line 74. Output box 72 has usual electrical receptacles. Inaddition, output box contains an emergency stop switch 74 having a line76 which connects with relay box 62. In addition, output box 72 has anover-temperature sensor 78 also connected to relay box 62 by means of aline 80.

The AC generator system 12 disclosed above takes advantage of the factthat the ECM 22 accurately controls the RPM of engine 14 under a varietyof circumstances including conditions where the engine control modulemaintains a preselected RPM. In certain vehicles having the capabilityto connect a power takeoff unit or PTO, there is a feature within theECM 22 and transmission control module 26 known as the PTO program. ThePTO program dictates the prime mover to operate at an RPM that ismaintained essentially constant but at a level higher than the normalRPM of the vehicle when it is operating at normal idle. For example, ifthe normal idle of a vehicle is under 1,000 RPM, the PTO programcontrols to 1,150 RPM. The drive ratio in housing 48 is selected so thatthe RPM of the AC generator 44 would be at its optimum to replicate autility sine wave. Generally speaking, the AC generator's optimum RPM is3600 for 60 cycles AC in the U.S. and 3000 RPM for 50 cycles foundoutside of the U.S. Thus the RPM of the generator 44 is extremelyaccurately controlled by virtue of the governing aspect of the enginecontrol module 22 which varies the quantity of fuel delivered to theengine 14 to account for variations in mechanical load when theelectrical loads through output box 72 are varied.

As pointed out before, relay box 62 plays a key role in enablingoperation of solenoid 56 so that the AC generator system is onlyoperated when conditions are safe. Thus the following conditions mustexist before solenoid 56 can be engaged: (1) automatic transmission inpark as sensed through line 71, (or if a manual transmission, in neutralwith vehicle parking brake set), (2) operator switch 36 on as sensedthrough line 68, (3) ignition switch 32 on as sensed through line 66.When these are present, the solenoid is engaged and when the ignitionswitch 32 is turned to start the engine 14, the solenoid 56 engages thePTO unit 50 to drive AC generator 44. The cruise control resume switch40 or PTO set position on the operator switch 36 is activated to placethe engine 22 in the PTO program for optimum operation of the ACgenerator 44. The AC generator 44 supplies electrical power through theoutput box 72. This continues until either: (1) the operator switch 36is turned off, (2) the ignition switch 32 is turned off, (3) theemergency switch 74 in output box 72 is activated, or (4) theover-temperature sensor 78 indicates too high a temperature throughoutput box 72. Thus it is seen that the AC generator system efficientlyutilizes existing sophisticated controls in the vehicle 10 to producehighly accurate and rugged electrical energy. It should be also notedthat for vehicles having automatic transmissions with a PTO, the lock-upswitch in the transmission is activated when the PTO is engaged.Accordingly, the responsiveness of the ECM to RPM variations due to loadis greatly enhanced, thereby enabling an accurate regulation of RPM.

It should also be noted that the mechanical input into the generator 44,while shown as coming from the PTO, may be also derived from anyconvenient accessory output of the engine including accessory gearboxes, accessory belt drives and the like.

The system shown in FIG. 1 contemplates a mechanical connectiondescribed later between the transmission PTO unit 50 and the input tothe AC generator 14. The system shown in FIG. 2 employs a hydraulicdrive, generally indicated by reference character 82, which isinterconnected to the vehicle 10 by a mechanical connection 84 fromengine 14 to a hydraulic pump 86. It should be noted that the mechanicalinput from 84 may either be an accessory gear drive or belt drive oreven a PTO depending upon the particular engine/transmissioncombination. In any event, the mechanical input 84 rotates hydraulicpump 86 to supply fluid under pressure through line 88 past adjustableflow control 90 to hydraulic motor 92 which has as its output themechanical input 46 to the AC generator 44. A return line 94 extends toa hydraulic reservoir 96 having a feed line 98 to hydraulic pump 86.

Details of the hydraulic drive 82 will not be discussed in order to aidin an understanding of the present invention. However, typical hydraulicdrives may consist of a gear pump 86 having its output regulated by anadjustable flow control 80 to a gear motor 92 having an output RPMcontrolled by flow as regulated by flow control 80. Alternately,hydrostatic drives involve multi-piston hydraulic pumps andcorresponding multi-piston hydraulic motors. The translatory movement ofthe pistons is translated into rotary movement by virtue of a wobbleplate. Variations may come in the form of flow control or mechanicalvariations in the components in order to provide a predetermined RPMratio between the output of the engine 14 and the input to the ACgenerator 44.

As in the case with the system set forth in FIG. 1, the adjustable flowcontrol 90 is set to produce an RPM ratio that takes into account thepreselected engine RPM and the required RPM for the AC generator.

The enablement features of relay box 62 are similar to those for FIG. 1depending upon the engine transmission interconnections and controls.

Still another variation in the generator control system 12 is found inFIG. 3 wherein a hydraulic drive is adapted to control the AC generatorwhen the vehicle 10 is operated on the highway with varying RPMs fromoutput shaft 20. In this case, a hydraulic drive 100 is connectedbetween an output shaft 102 of the PTO 50 and the input shaft 46 to theAC generator. Hydraulic drive 100 comprises a hydraulic pump 104 drivenby input shaft 102 and supplying fluid through line 106 via adjustableflow control 108 to hydraulic motor 110 which has its output connectedto input shaft 46 for AC generator 44. A return line 112 extends to ahydraulic reservoir 114 and in turn has a feed pipe 116 to the hydraulicpump 104. Additionally, the hydrostatic drive 100 has a speed sensor andflow control module 118, which acts to vary the RPM ratio between thePTO unit and the drive to the AC generator. Speed sensor 118 receivesengine RPM (and therefore vehicle speed) inputs via line 120 extendingto relay box 62 and to the engine control module 70. The details of howthis operates will not be discussed to simplify an understanding of thepresent invention. However, it is sufficient to say that the speedsensor and flow control module 18 varies the RPM ratio between the PTOunit and the input shaft 46 to AC generator to maintain a specific RPMfrom AC generator 44 as sent to the speed sensor 118 via line 122. Thispreselected RPM is maintained regardless of the variation in RPM ofengine 14 and transmission 16.

What has been described above is how the generator system of the presentinvention integrates with the operational control and safety system ofthe vehicle 10. Reference is now directed to FIGS. 4 through 8 whichshow a specific implementation of the system described in FIG. 1. FIGS.4 though 8 show only those portions of the vehicle 10 necessary toproperly explain the present invention. All the other details have beenomitted to allow a simplification and focus on a proper understanding ofthe invention.

Vehicle 10 has a pair of frame rails 130 and 132. The frame rails 130and 132 are generally parallel and form the structural support for manycommercial vehicles. Within the frame rails 130 and 132, the engine 14(not shown) is mounted in such a way that its crankshaft axis identifiedat 134 is generally parallel to the longitudinal axis of the frame rails130 and 132. It should also be noted, however, that the engine centerline may be oriented other than as shown and still achieve the benefitsof the present invention. The transmission 16 is secured to the engineso that the input face 18 to the transmission 16 is coaxial with theaxis 134 of the engine. The primary power output from the enginetransmission 16 is not shown in order to simplify an understanding ofthe present invention. It should be apparent to those skilled in the artthat it will drive a differential axle at the rear of the vehicle. Inaddition, it may have an additional output to provide all-wheel-drive byconnecting to a similar differential or drive arrangement at the frontof the vehicle. As herein shown, the transmission 16 is an automaticmanufactured by Allison Division of General Motors. It should beapparent that other transmission brands may be used with equivalentadvantage. Transmission 16 has a power takeoff or PTO 50 which has astandard SAE 6 or 8 bolt mounting plate configuration that is equivalentfor all commercially available transmissions.

As shown particularly in FIG. 5, PTO 50 has a universal joint 136 at itsoutput which connects to a torque tube 138 extending aft from vehiclecompartment 140 substantially housing the prime mover consisting of theengine 14 and transmission 16. The prime mover compartment 140 is shownin solid outline in FIG. 4 and in dashed outline in FIG. 5. The torquetube 138 extends to a universal joint 142 forming the input to an RPMratio device 48 that connects to AC generator 44. As shown particularlyin FIG. 4, RPM ratio device comprises a housing 144 having journaledtherein an input pulley 146 and output pulley 148. Output pulley 148 isfixed to the input 46 to AC generator 44. Input shaft 46 is a shaft andpulley 148 is secured to the shaft in normal fashion. A belt 150 extendsbetween pulleys 146 and 148. The belt 150 is shown as a toothed belt toprovide increased torque carrying capacity. It should be noted, however,that a non-toothed belt and other forms of RPM ratio manipulation may beemployed with equivalent advantages. Specifically, intermeshing gearsmay also be employed for this application. As mentioned in thediscussion of FIG. 1, the ratio between the power takeoff output RPM andthe required input of AC generator 44 is selected to match the optimalRPM conditions for AC generator 44. This is done by selecting thediameters of pulleys 148 and 146 to achieve the required RPM.

The PTO 50 is shown as being engageable and disengageable with theoutput of transmission 16. FIG. 7 shows one implementation of thisfeature. A housing 152 is secured to the transmission housing 154 byappropriate screws 156 (see FIG. 4). Housing 152 is positioned over atransmission PTO drive gear 158 shown in FIG. 7 and in FIG. 4. An outputshaft 160 is journaled in housing 152 by appropriate bearings 162 and164 to journal shaft 160 on an axis parallel to the axis 134 of theengine 14 and transmission 16. The end of shaft 160 extending fromhousing 152 connects with universal joint 136. Shaft 160 has anelongated splined section 166 on which a spur gear 168 is telescoped.Spur gear 168 has internal splines 170 which cause gear 168 to rotatewith shaft 160 but permits it to be axially displaceable from the solidposition shown in FIG. 7 where the AC generator is disengaged from theprime mover to the leftmost position indicated by partial lines in FIG.7 where the AC generator is engaged with the prime mover. Spur gear 168has an integral extension 172 and groove 174 which receives a fork 176.Fork 176 is secured to the moveable output shaft 178 of a solenoid 180.Output shaft 178 of the solenoid 180 is biased to its solid positionshown in FIG. 7 by a spring 182 acting against a flange 184 on shaft 178and an end wall 186 in solenoid 180. Solenoid 180 then holds the gear168 in its disengaged position by virtue of the spring and whenelectrical power is applied to solenoid 180 by line 60, the output shaft178 is displaced to the left as shown in FIG. 7 thus meshing gear 168with the transmission accessory drive gear 158 to cause the AC generatorto be operated. It should be noted particularly in FIG. 4 that housing152 of PTO 50 has an angled outer configuration so as to clear theexisting wall of prime mover compartment 140. This is particularlyadvantageous for applications where the PTO is desired to be taken offof a side of the transmission opposite to the provision made by theoriginal equipment manufacturer.

As pointed out earlier, the AC generator 44 is positioned at a pointsubstantially outside of the prime mover compartment 140. In vehicles ofthis type, it is common to have frame rails. The brackets shown in FIG.8 show in detail how the AC generator 44 and RPM ratio device 48 may bemounted in the vehicle frame without having to drill holes or otherwisecut into the structural integrity of the frame rails. As shownparticularly in FIG. 8, frame rail 132 from which the AC generator 44will be mounted has a C-shaped cross-section with lips 188 extendingtoward one another. The bracket for mounting the AC generator 44 and RPMratio device 48 comprises a pair of fingers 190 extending from verticalbrackets 192 and in a direction generally at right angles to the axis ofrotation of AC generator 44. Brackets 192 extend vertically beyond theupper and lower extent of frame 132 and connect to plates 194 by meansof fasteners 196 to sandwich the lips 188 of frame rail 132. A pair oflongitudinal support plates 198 interconnect brackets 190 and provide amounting platform for the AC generator 44. It should be noted thatbecause the frame 132 is generally of uniform cross-section, thevertical brackets 192 and plates 194 may be easily positioned in anoptimal location along frame rail 132 to provide optimum positioning ofAC generator where a space is available within the frame of the vehicle10. It should be noted that in practice the space within the frame ofthe vehicle is usually crowded with a significant number of componentsincluding the main drive shaft to the rear axle, the catalytic converterand muffler and appropriate interconnecting exhaust pipe. In addition,items like a fuel tank could be contained within the frame. By clampingthe mounting for the AC generator in the manner described above, greaterflexibility is realized to fit the AC generator 44 into an appropriatelocation.

As shown particularly in FIG. 6, the electrical output from AC generator44 through line 74 extends from AC generator 44 through the frame 132 tothe output box 72 (not shown in FIG. 6). However it should be noted thatat least a portion of the electrical line 74 extends through frame 132for added protection as it extends to outlet box 72.

Also with reference to FIG. 6, the load-carrying portion of vehicle 10is indicated by dashed lines 200 and it is apparent that the ACgenerator 44 is contained within the frame adjacent the load carryingsection 200. This is advantageous because the outlet box 72 is alsopositioned in the load carrying section making it convenient toconstruction equipment and supplies to be used by an operator.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiment has been shown and described and that allchanges and modifications that come within the spirit of the inventionare desired to be protected.

1. A vehicle mounted AC electrical generator system comprising: a primemover controlled by a control system to a predetermined RPM, an ACelectrical generator positioned in said vehicle and having a mechanicalpower input connection for driving said AC electrical generator toproduce electricity, a transfer device receiving mechanical power fromsaid prime mover and transferring said mechanical power to said ACelectrical generator mechanical power input connection, said transferdevice having a means for matching the RPM of the prime mover to theoperational RPM of said AC electrical generator.
 2. Apparatus as claimedin claim 1 wherein said transfer device increases the RPM from saidprime mover to said AC electrical generator.
 3. Apparatus as claimed inclaim 2 wherein said prime mover operates at preselected RPM and overoperational RPM range as dictated by said control system, and whereinsaid prime mover rotates the transfer device when said prime mover is atsaid preselected RPM.
 4. Apparatus as claimed in claim 1 wherein thecontrol system for said prime mover has an electronic control module. 5.Apparatus as claimed in claim 1 wherein said prime mover has a powertakeoff unit (PTO) and said transfer device connects between said PTOand the mechanical power input connection of said AC electricalgenerator.
 6. Apparatus as claimed in claim 5 wherein said transferdevice comprises: a connection between the rotary output of said PTO anda point adjacent said AC electrical generator, and a means forestablishing a predetermined RPM ratio between said rotatable output RPMand the input RPM of said AC electrical generator.
 7. Apparatus asclaimed in claim 6 wherein said means for establishing RPM ratioincreases the RPM of said PTO output.
 8. Apparatus as claimed in claim 6wherein said AC generator operates at 3600 RPM.
 9. Apparatus as claimedin claim 6 wherein said AC generator operates at 3,000 RPM. 10.Apparatus as claimed in claim 4 wherein said electronic control systemsupplies fuel to said prime mover at a rate and condition to vary thepower output of said prime mover, whereby said operational RPM of saidAC electrical.